The present invention relates generally to the field of electronic locking or access-control systems where a user wishing to gain access to a restricted area, or to some service such as the use of a cash-dispensing machine, presents to a receiving apparatus a token which transmits identification data indicative of the user's authority to gain such access. More particularly, the invention relates to a contactless-identification system of the kind where the receiving apparatus includes an alternating magnetic field generator and the token includes a transponder powered by induction from said field.